U.S. Pat. No. 4,678,051 (Dugle) titled “Rectilinearly Traveling Vehicle” discloses a vehicle having a first travelling assembly configured to move a vehicle in a first direction and a second travelling assembly to move the vehicle in a second direction, orthogonal to the first direction. U.S. Pat. No. 9,616,948 (Ben-Tzivi) titled “Active Docking Mechanism for Modular and Reconfigurable Robots” teaches similar principles to those taught in the Dugle reference as applied to robots.